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Engine Fluttering Sound

Looking for some ideas.

The bike currently has 60K miles and recently started running strange. I would best compare it to a 8 cylinder running on 7 cylinders. When I'm below 3000 RPMs, the engine shutters a little and makes what I'd call a fluttering sound on acceleration. Above 3000 RPMs, it feels almost normal.

My first thought was a bad spark plug so I purchased two new EOM spark plugs and they have been replaced. My second thought was maybe a bad plug wire so closed the garage door and turned out the lights to look for an ark from the wires to some nearby metal. I saw no arks. I have checked the oil level and it is good. One thing I have not checked is the air filter but would not expect such a drastic change overnight from a dirty air filter. I could be wrong.

I'm starting to wonder if it is a slightly clogged fuel filter but looking for ideas now. This idea come to mind because a new fuel station got put in 5 block from my house and I started using this station. They offer non-ethanol fuel so I switched over. That could be a coincidence or not. I would rather not just throw parts at it and would like to see what the community has to say.

Thanks in advance. This is my daily driver so would really like to get her running good again.

Thanks, I was worried about that. I had not researched its location yet but had a bad feeling it might be there.

A problem for sure. Does it do it when you roll on the throttle quickly or just any acceleration under 3000? What if you are above 3000 rpm and roll on the throttle hard/quickly? Fuel filter at 60,000 isn't a bad idea though. Is it a filter in the tank or a screen/sock?

Rather than blindly replace parts( like most “auto technicians” nowadays), you could try some diagnosis. Have you done a compression test? Hooked it up to an oscilloscope to see if everything is firing correctly?
It does sound like an electrical gremlin, but bad injectors can mimic that too. Have you tried running a can of Seafoam through it yet?

A problem for sure. Does it do it when you roll on the throttle quickly or just any acceleration under 3000? What if you are above 3000 rpm and roll on the throttle hard/quickly? Fuel filter at 60,000 isn't a bad idea though. Is it a filter in the tank or a screen/sock?

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Pretty much anytime I accelerate under 3000 rpm but it shutters a bit worse if I accelerate hard.

Rather than blindly replace parts( like most “auto technicians” nowadays), you could try some diagnosis. Have you done a compression test? Hooked it up to an oscilloscope to see if everything is firing correctly?
It does sound like an electrical gremlin, but bad injectors can mimic that too. Have you tried running a can of Seafoam through it yet?

HTH....
Let us know what you find!

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I have considered some form of "injector cleaner" but have not tried that yet. I have used seafoam on cars but never a motorcycle. I'm sure it couldn't hurt in small doses.

I have considered some form of "injector cleaner" but have not tried that yet. I have used seafoam on cars but never a motorcycle. I'm sure it couldn't hurt in small doses.

Mix according to the instructions. I have had very good results using AmsOil fuel cleaner when My daughter let her Rebel 250 sit to much for two years. It was given to her younger sister and I couldn't get it above 50 and I used to be able to get it up to 60-65 mph with my 6'3" bulk. Doubled the dose of cleaner in a batch of new gas. Went for a 70 mile ride. By the time I got back I was getting it to 60 on the level. Try a good cleaner. I use seafoam for storage in my bikes over the winter.

Some time ago I fought a shuddering problem on a V6 minivan engine. It was subtle and only occurred when it shifted to overdrive at around 45 mph and the load was fairly high, in other words, a low RPM shudder. Over the course of probably two years I tried this and that, plugs, sensors, wires, even transmission treatments. In the end it was cured when I changed the coil pack. So while I’ve not heard of a bad ignition coil on an NC, keep way in the back of your mind that it could cause this.

Was the bike subject to a high pressure wash or a monsoon lately?

I don’t know if this thread fits your symptoms, but it’s worth noting. This one ended up being a bad fuel pump.

Some time ago I fought a shuddering problem on a V6 minivan engine. It was subtle and only occurred when it shifted to overdrive at around 45 mph and the load was fairly high, in other words, a low RPM shudder. Over the course of probably two years I tried this and that, plugs, sensors, wires, even transmission treatments. In the end it was cured when I changed the coil pack. So while I’ve not heard of a bad ignition coil on an NC, keep way in the back of your mind that it could cause this.

Was the bike subject to a high pressure wash or a monsoon lately?

I don’t know if this thread fits your symptoms, but it’s worth noting. This one ended up being a bad fuel pump.

I rarely wash it so no on the pressure washing but it has been subject to rain. No high pressure rains though. She overheated on me twice yesterday when riding home which has two quick stops and I'm rolling about 50 mph the entire time. Here is a thought and would like to hear anyone's input. The last time I checked the valve clearance was about 20k miles ago. Could a valve out of adjustment cause this "fluttering/shuttering" and the overheating? I'm grasping at straws now but I'd rather solve this myself without taking it to the shop.